Those who see only monotony in monogamy take multiple partners — and may be devoutly religious to boot.

By day, he’s an Atlanta real-estate investor, a self-described political conservative, a member of a Methodist church, son of a Southern Baptist pastor.

After hours, he’s known as “Mr. Big,” a columnist for PolyamoryOnline.org. His family — a wife and five children — lives with a couple who have four children. Each husband is romantically involved with both wives, and vice versa.

As “Mr. Big” and his wife entered the polyamorous relationship with the other couple two years ago, he said he began to study the Bible more closely and “found something fishy.”

“I still haven’t figured out when Christianity and Judaism went from being polytype religions to strictly monogamous ones,” said “Mr. Big,” who asked not to be identified to protect his children’s privacy.

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Because Old Testament figures such as King David had multiple wives, he said, it was only logical that in today’s society, in which men and women are equal, that women should be allowed multiple partners.

That doesn’t mean it’s at all respectable. “Our family has to keep things behind a little bit of a veil,” he said. “Nobody wants to hear about your sex life at church.”

That veil may be lifting — however slightly and slowly — as faith-minded polyamorists come out of the sexual closet. Mr. Big is just one of many polyamorists who say their multiple romantic relationships are intimately linked to their faith and values, even as their celebration of nonmonogamy often earns a cool or hostile reception from others.

Harlan White gathers his “tribe” — his three adult partners and other adults with whom they’re romantically involved — for an unconventional family dinner every Wednesday. Multiple love relationships are pursued openly.

“We make a conscious effort to create something that feels like an extended family,” said White, 57, a medical professional who lives on the West Coast but asked that the city not be named. “One of the values of polyamory is building networks of relatedness that transcend the nuclear family.”

White is board president of the group Unitarian Universalists for Polyamory Awareness. Polyamory seems to run in his family: His sister, Valerie White, has what she calls an “intentional family.” She shares the parenting of 5-year-old twins with two other polyamorous adults.

Her Unitarian Universalist congregation on Boston’s South Shore has been “completely accepting,” she said, even electing her president.

The term polyamory was added to the Oxford English Dictionary only last year but first came into circulation in the late 1980s. However, polyamorists are quick to note that such arrangements have been around for centuries.

Members of the early 20th century “Bloomsbury Group” of English writers and artists — Virginia Woolf and others — had intertwined love lives. More recently, investing guru Warren Buffett had what his wife, Susan, called “an unconventional marriage,” in which Buffett openly consorted, for decades, with a close friend of his wife, according to The New York Times.

In a more religious vein, the 19th-century utopian Oneida Community engaged in theologically Christian “complex marriage,” in which every adult male was married to every adult female. In the 1970s and ’80s, the San Francisco commune Kerista was based on group marriage with an overlay of New Age spirituality.

Lisa Davis, 44, embraced polyamory before she even knew what it meant. The convert to Hinduism says the practice is consistent with ancient Hindu stories of polygamy and her experience of communal living.

Davis was living in Florida when her husband, a politically conservative Air Force veteran who traveled for months at a time, suggested that his close friend assume the role of “surrogate husband and father” when he was away. The relationship evolved from platonic to romantic to sexual, all with her husband’s consent.

“I’m not sure why our culture is so hell-bent on monogamy. It’s so impractical; look at all the help you need raising children,” said Davis, pointing to stories from Hindu scripture in which kings or gods had multiple wives who supported and helped one another.

Tolerance can vary. Some Christians such as “Mr. Big” keep their family life veiled from public view. Others are more public, but still the reception can be chilly, even within liberal church circles.

“Ironically, some resistance has come from members of the gay and lesbian community, who have said we are ‘muddying the waters’ and diverting people from the goal of legalizing same-sex marriage,” said Kathleen Reedy, 71, a divorcee who heads the Washington, D.C.-area chapter of Unitarian Universalists for Polyamory Awareness.